1. Field of the Invention
The present invention relates to a method of causing a developer container to decrease in volume in substantially a preselected shape, a developer replenishing device using the developer container, and an image forming apparatus including the same.
2. Description of the Background Art
It is a common practice with a printer, copier, facsimile apparatus or similar image forming apparatus to form a toner image with a developer stored in a developing unit and implemented as only toner or a toner and carrier mixture. Generally, because toner is consumed as image formation is repeated, a toner bottle, toner cartridge or similar toner container, storing fresh toner therein, is removably mounted to the apparatus body for replenishing the fresh toner to the developing unit. To discharge toner from such a toner container, an auger may be disposed in the toner container for conveying the toner to the outlet of the container. Alternatively, the toner container may be implemented as a screw bottle rotatable about its axis to convey toner toward an outlet little by little.
The auger scheme is, however, not practicable without a rotatable member disposed in the toner container, resulting in a sophisticated structure. In addition, the rotatable member, which needs replacement, increases the cost of the toner container. On the other hand, the screw bottle scheme is simple because no members are present in the bottle. However, because the screw bottle is formed with an outlet at one side thereof and positioned substantially horizontally, it can accommodate only a relatively small amount of toner and is slippery and difficult to hold by hand in the event of replacement.
In light of the above, there has been proposed a toner conveying system in which a suction pump sucks toner out of a toner container and delivers it to any desired position. This system allows the toner container to be implemented as a container that is flexible and therefore foldable in a compact configuration after use. The toner container thus folded up can be collected by the manufacturer at low cost.
The flexible toner container stated above can decrease in volume in accordance with the consumption of the toner stored therein. Also, when such a toner container runs out of toner, its volume can be reduced if air inside the container is sucked out. The toner container reduced in volume is easy to handle at the time of replacement and does not have to be folded up later, contributing to the reduction of collection cost.
However, the problem with the flexible toner container is that the container cannot decrease in volume in a preselected shape due to collapse, twist and so forth. It follows that even the toner container reduced in volume cannot be efficiency stored or transported after collection. Should the toner container reduced in volume be neatly folded later, extra work would be required and would therefore cancel the advantage of a decrease in volume. Moreover, it is likely that much toner is left in the toner container because of such an irregular decrease in volume.
Technologies relating to the present invention are disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 8-272204 and 2003-43797.